Praise ye the god of iron

Iron mediated toxicity and programmed cell death: A review and a re-examination of existing paradigms

Iron is an essential micronutrient that is problematic for biological systems since it is toxic as it generates free radicals by interconverting between ferrous (Fe²⁺) and ferric (Fe³⁺) forms. Additionally, even though iron is abundant, it is largely insoluble so cells must treat biologically available iron as a valuable commodity. Thus elaborate mechanisms have evolved to absorb, re-cycle and store iron while minimizing toxicity. Focusing on rarely encountered situations, most of the existing literature suggests that iron toxicity is common. A more nuanced examination clearly demonstrates that existing regulatory processes are more than adequate to limit the toxicity of iron even in response to iron overload. Only under pathological or artificially harsh situations of exposure to excess iron does it become problematic. Here we review iron metabolism and its toxicity as well as the literature demonstrating that intracellular iron is not toxic but a stress responsive programmed cell death-inducing second messenger.

Alcohol and the liver

PURPOSE OF REVIEW

To apprise the reader of advances in 2005 in the epidemiology, pathogenesis, prognosis and treatment of alcoholic liver disease. Alcohol use has declined in developed countries, but the opposite is true elsewhere; alcoholic liver disease is a considerable burden worldwide.

RECENT FINDINGS

Genetic mechanisms for alcoholic liver disease are being discovered in addition to aggravating cofactors, such as hepatitis C, obesity and iron overload, and ameliorating ones, like coffee and tea drinking. The involvement of the innate immune system and the mechanisms of apoptosis in alcoholic liver disease are better appreciated, especially the emerging role of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). Steroid use and nutrition for alcoholic hepatitis are being refined, and the validity of the model for end-stage liver disease (MELD) score in predicting the outcome of alcoholic liver disease is upheld. Recidivism after liver transplantation for alcoholic liver disease adversely impacts long-term survival.

SUMMARY

Inroads are being made into the genetics of alcoholic liver disease and new phenomena are being uncovered in its pathogenesis, but safe and effective therapies for both alcoholic hepatitis and alcoholic cirrhosis are still wanting.